- The residues are mapped based on positions according to Aneurinibacillus migulanus (former Brevibacillus brevis) GrsA-A numbering [101]. Amino acid residues in the NRPS code are highlighted according to their physicochemical properties: acidic (red), small/hydrophobic (grey), aromatic/hydrophobic (ocher), hydrophilic (green), and basic (blue)